1. Field of the Invention
The present invention relates to an information processing apparatus, an image forming apparatus, and an information processing program.
2. Description of the Related Art
Conventionally, some information processing apparatuses have a central processing unit (CPU) interface (I/F) that mediates communications in a CPU. Some of such information processing apparatuses have capabilities of analyzing, when an error occurs, contents accessed by the CPU, and finding the location causing the error. For example, by a known method, a measuring instrument is connected to the CPU I/F to observe the CPU I/F, and when an error occurs, a result of the observation is used in analyzing contents accessed by the CPU to find the location causing the error. However, by this method, finding the location of the cause of the error using the observation result has been an extremely difficult task. Furthermore, in an information processing apparatus with a built-in CPU, it has been difficult to connect a measuring instrument to the CPU I/F, further making it difficult to analyze the contents accessed by the CPU.
In some recently developed technologies, such as those disclosed in Japanese Patent Application Laid-open No. 2006-011969, Japanese Patent Application Laid-open No. 2008-287319, and Japanese Patent Application Laid-open No. 2004-185318, an access analyzing circuit for analyzing the contents accessed by the CPU is incorporated near the CPU I/F, the result of the analysis of the access analyzing circuit (analysis result) is stored in a random access memory (RAM) as a log, and the log thus stored in the RAM is output, instead of connecting a measuring instrument to the CPU I/F. More specifically, such an information processing apparatus includes a built-in CPU in or an external CPU, an external RAM, a read-only memory (ROM), an input/output (IO) device, and a serial communication interface, and also includes a decoding circuit that analyzes which location has been accessed by the CPU based on an address, a circuit for analyzing the contents accessed by the CPU, and a log receiving and transmitting direct memory access (DMA) that outputs the result of the analysis as a log.
In these conventional technologies, the result of the analysis is obtained in response to a command issued by the CPU, and stored as a log. Therefore, the log can be stored as long as the CPU is operating normally. However, once an error occurs in the CPU and the CPU becomes incapable of operating normally, the log might not be stored even if some serious error relating to the error occurred immediately before the occurrence of such an error. Moreover, a watchdog timer, for example, may be used to reset the CPU when a certain time period has elapsed since the error occurred in the CPU so that the information processing apparatus is recovered. However, when the log is analyzed later in time, such an analysis may take a long time because the operational timing at which the error occurred cannot be identified.
The present invention is made in consideration of the above, and an object of the present invention is to provide an information processing apparatus, an image forming apparatus, and an information processing program that can store contents accessed by a CPU during the period from when the normal operation of the CPU is confirmed until immediately after occurrence of an error in the occasion of any occurrence of an error in the CPU.